The Cowboys have fallen behind Denver, Seattle and San Francisco in merchandise sales. (Tom Pennington/Getty Images)

The Dallas Cowboys, who were nicknamed "America's Team" during the 1978 season, could be seeing their nickname fading away if recent NFL merchandise sales are a true indicator.

The Cowboys were atop merchandise sales for a number of years thanks to their popularity around the world, but the team recently slipped to No. 4, according to the Dallas Morning News.

The Seattle Seahawks, Denver Broncos and San Francisco 49ers all passed the Cowboys in merchandise sales following the 2013 regular season, which comes as no surprise given their success over the past two years. Dallas has failed to make a deep playoff run since winning three Super Bowls in four years back in the mid-1990s.